Season extension structures like high tunnels make it possible to produce coldtolerant crops during winter months for both a longer cropping season and a winter market season. The effects of location and planting date on the fresh yield of several cultivars of Asian greens (Brassica rapa L.), lettuce (Lactuca sativa L.), and spinach (Spinacia oleracea L.) were examined at Moscow, ID/Pullman, WA, and Vancouver, WA, a cold temperate climate and a mild marine climate, respectively. In Winter 2005-06, 20 cultivars were evaluated and in Winter 2006-07 a subset of 12 cultivars were evaluated. Location impacted yield, and higher yields overall were attained at Vancouver than at Moscow/Pullman, likely as a result of more consistent, warmer soil and air temperatures as well as increasing irradiance in February and March at Vancouver. Asian green cultivars had the highest overall yield resulting from faster growth compared with spinach and lettuce cultivars at both locations. Although most lettuce cultivars grew throughout the winter, further research is needed to identify the most suitable cultivars, seeding dates, and planting densities to optimize winter production of this crop and for Asian greens and spinach. Planting date influenced yields with the highest yields obtained for the third planting date for all trials except at Moscow/Pullman in the second year. Overall, this research suggests that it is possible to grow many cold-tolerant cultivars of Asian greens, spinach, and lettuce in a high tunnel during the winter months in both mild and cold temperate northern climates.

While demand continues to grow and prices for organic grains have remained almost double those of conventional grains, few growers in the dryland wheat production region of Eastern Washington produce organic grain. Growers have cited weed control constraints as a top factor preventing adoption of organic production practices. In organic systems, inherent competitive ability of crops is very important in managing and preventing weed infestations. The objective of this study was to identify crop species that could reduce weed pressure and compete with perennial weeds in a wheat (Triticum aestivum) rotation. To assess weed suppressive ability of alternative rotational crops, relative total weed biomass and relative biomass of two perennial and three annual weed species were examined over 4 years in three organic cropping systems where winter wheat was in rotation with alternative crops, as part of a long-term study examining dryland organic wheat production. Three years of continuous alfalfa (Medicago sativa) production reduced Canada thistle (Cirsium arvense) biomass during the alfalfa production phase, and reduced Canada thistle biomass in winter wheat following alfalfa, compared with wheat following winter pea (Pisum sativum). Alfalfa was competitive with wild oat (Avena fatua), though it competed poorly with winter annual grass weeds. Spring barley (Hordeum vulgare), when established successfully, suppressed jointed goatgrass (Aegilops cylindrica) more than winter triticale (xTriticosecale), winter wheat, and spring wheat, and demonstrated some competitiveness toward field bindweed (Convolvulus arvensis). Winter triticale competed poorly with field bindweed, but suppressed Canada thistle and downy brome (Bromus tectorum). All alternative rotational crops contained lower weed biomass than winter pea, the crop typically rotated with wheat in the region. Organic and conventional growers could gain benefits in perennial and winter annual weed suppression by incorporating alternative rotational crops into wheat rotations.

Climate-friendly best management practices for mitigating and adapting to climate change (cfBMPs) include changes in crop rotation, soil management and resource use. Determined largely by precipitation gradients, specific agroecological systems in the inland Pacific Northwestern U.S. (iPNW) feature different practices across the region. Historically, these farming systems have been economically productive, but at the cost of high soil erosion rates and organic matter depletion, making them win-lose situations. Agronomic, sociological, political and economic drivers all influence cropping system innovations. Integrated, holistic conservation systems also need to be identified to address climate change by integrating cfBMPs that provide win-win benefits for farmer and environment. We conclude that systems featuring short-term improvements in farm economics, market diversification, resource efficiency and soil health will be most readily adopted by farmers, thereby simultaneously addressing longer term challenges including climate change. Specific "win-win scenarios" are designed for different iPNW production zones delineated by water availability. The cfBMPs include reduced tillage and residue management, organic carbon (C) recycling, precision nitrogen (N) management and crop rotation diversification and intensification. Current plant breeding technologies have provided new cultivars of canola and pea that can diversify system agronomics Pan et al.Win-Win Scenarios for Farm and Climate and markets. These agronomic improvements require associated shifts in prescriptive, precision N and weed management. The integrated cfBMP systems we describe have the potential for reducing system-wide greenhouse gas (GHG) emissions by increasing soil C storage, N use efficiency (NUE) and by production of biofuels. Novel systems, even if they are economically competitive, can come with increased financial risk to producers, necessitating government support (e.g., subsidized crop insurance) to promote adoption. Other conservation-and climate change-targeted farm policies can also improve adoption. Ultimately, farmers must meet their economic and legacy goals to assure longer-term adoption of mature cfBMP for iPNW production systems.

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Raindrop‐induced crusting of mineral soils supporting wheat (Triticum aestivum L.) in the semiarid US Pacific Northwest reduces seedling establishment of late summer‐seeded winter crops during dry, hot conditions. Canola (Brassica napus L.) integration is diversifying regional food, feed and fuel global markets. Subsequent shifts in recycled crop residue characteristics, including Si and crop fiber, may shift soil characteristics of traditional wheat‐dominated systems, potentially affecting their propensity to form soil crusts. In a greenhouse study, wheat and canola were fertilized with varying N rates. Increased N supply increased transpiration, shoot weight, and hemicellulose and cellulose yields, but with only minor increases in shoot Si and lignin yields. Both crops had similar increases in root Si with greater N‐stimulated transpiration. Two subsequent soil incubations were conducted to determine how Si, N fertilization, and crop residues from wheat and canola affected soil properties. In the first incubation, Si was applied as aqueous H4SiO4, which increased soil amorphous and water‐soluble Si (Siam and Siws), physical resistance, and crust thickness. Electron micrographs showed increased amorphous material, presumably a Si precipitate, on soil particles with increased Si application. Second, two Ritzville soils were treated with the canola or wheat shoot residues with and without N fertilizer. Nitrogen lowered soil pH, Siam, Siws, surface resistance, and crust thickness; however, first‐time application of crop residue types had no short‐term effect on these parameters. Any impacts of lower Si returned by lower Si crop residues on soil physical properties likely require several rotational cycles of Si crop uptake and residue returns. Core Ideas Wheat and canola Si increases with N fertilizer, differently correlated to crop transpiration. Si residue contents are ranked: wheat shoot residue > canola shoot > wheat root = canola root. Canola residue returns less Si but more lignin to soil surface than wheat. Long‐term wheat Si recycling may increase soil physical impedance of seedling emergence. N fertilization lowers soil pH, soluble and amorphous Si, surface resistance, and crust thickness.